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A Roman provincial city and its contamination legacy from artisanal and daily-life activities

New publication by Genevieve Holdridge, Søren M. Kristiansen, Gry H. Barfod, Tim C. Kinnaird, Achim Lichtenberger, Jesper Olsen, Bente Philippsen, Rubina Raja and Ian Simpson.

2021.06.10 | Mie Lind

Photo of the Artemis Temple in the archaeological site of ancient Gerasa. In the background, the modern city of Jerash as well as surrounding hill tops. In the new study published in PLOS ONE, researchers have analysed the contamination both within the ancient city and in its hinterlands. Photo: The Danish-German Jerash Northwest Quarter Project.

Metal contamination is often associated with modern industry and urbanity. However, modern contamination is not the only source with a global and local traceable impact. Roman industrial mining and smelting activities resulted in a global atmospheric impact observed in European bogs and Arctic and Alpine ice cores. In Roman cities, soil samples have revealed that the use of lead pipes in water supply systems resulted in metal contamination reaching levels similar to modern industrialization levels. Whereas contamination associated with mining and lead pipes is evident, the understanding of other causes of environmental contamination has hitherto been limited.

Contamination caused by artisanal and daily-life activities in Gerasa

In a new international study with first author Dr Genevieve Holdridge (former postdoc at the Department of Geoscience and Centre for Urban Network Evolutions [Aarhus University]), researchers have traced evidence of contamination caused by small-scale activities in the Roman, Byzantine, and Ummayad periods at the ancient city of Gerasa. This was done combining contextual archaeological evidence from the excavations of the Danish-German Jerash Northwest Quarter Project, OSL sediment chronologies (based on radiocarbon dating), and multi-elemental analyses of soils and sediments. Associated Professor Søren Munch Kristiansen from the Department of Geoscience and Centre for Urban Network Evolutions (Aarhus University) is one of the co-authors of the new study.

By combining pollution data from not only within the ancient city but also from its hinterland and the river valley (called a wadi) up- and down-steam the city, an unexpected pattern became clear. The ancient city was the hotspot of heavy metal pollution that is difficult to explain by ‘the usual suspect’ in ancient pollution studies: lead water pipes and mines,” says Søren Munch Kristiansen.

The elevated levels of lead, cobber, tin and arsenic in the city’s sediments correspond well with documented metal-related activities in Gerasa, such as coin minting and the production, use, and reuse of metal objects. However, archaeological finds yielded very little, if any, evidence of lead pipes used in the water management system in Gerasa. Hence, the high levels of especially lead and cobber in the modern-day urban soils and the river sediments down-stream seem mainly to be the result from the legacy of common, accumulative metal-related artisanal and daily-life activities within the city. Levels that accumulated over nearly a millennium until the devastating earthquake in 749 CE, after which the city was abandoned.

The contamination pathways of Gerasa in the Roman through Umayyad periods had unanticipated consequences for later occupants of the city and its hinterland. This study clearly showcase how urban small-scale activities, such as use and reuse of heavy metal sources, should be factored in order to fully understand regional and maybe even global-scale contaminant distributions – something that has previously been ignored in historical contamination studies. Hopefully, the case of Gerasa holds valuable lessons for sustainable middle-sized cities of both the past and the present.

Danish-German research at the urban site of Gerasa

The research in the newly published study in PLOS ONE was undertaken within the framework of the Danish-German Jerash Northwest Quarter Project. Two of the publication’s other co-authors, Professor Achim Lichtenberger (University of Münster) and Centre Director at Centre for Urban Network Evolutions Professor Rubina Raja (Aarhus University), head the excavation project in Jordan. Since 2011, they have worked at the archaeological site together with several specialist. Through the project’s high-definition approaches and full quantification methods combined with context studies and analyses from the natural sciences, they have provided several ground-breaking results from the urban contexts of Gerasa, and the new study is yet another testimony of this.

The Danish-German Jerash Northwest Quarter Project is supported by the Carlsberg Foundation, the Danish National Research Foundation under grant DNRF119 (Centre for Urban Network Evolutions [UrbNet]), the Deutsche Forchungsgemeinschaft, the Deutscher Palästinaverein, the Danish EliteForsk Award, and H. P. Hjerl Hansens Mindefondet for Dansk Palæstinaforskning.

Find out more

Read the paper here:

Holdridge, G., Kristiansen, S. M., Barfod, G. H., Kinnaird, T. C., Lichtenberger, A., Olsen, J., Philippsen, B., Raja, R. & Simpson, I. (2021). ‘A Roman provincial city and its contamination legacy from artisanal and daily-life activities’, PLoS ONE 16(6): e0251923. https://doi.org/10.1371/journal.pone.0251923

Further project links:

The Danish-German Jerash Northwest Quarter Project

Centre for Urban Network Evolutions (UrbNet)

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